The present invention relates to a closure for break-action firearms.
Hunting and target-shooting shotguns with two superimposed barrels, called over and under shotguns, are normally provided with a so-called break-action closure, in which the barrel assembly, which has at the breech the tenons or lugs, can rotate with respect to the closure block, i.e., the break-action, about a retention pivot which is arranged transversely.
The breech end of the barrel assembly must rest against the break-action without detectable play.
During firing, the pressure generated inside the bore of the barrel in fact stresses the wall of the barrel and of the breech and the force that would tend to propel the barrel forward is substantially counterbalanced by the retention pivot and by any other surface provided in the closure system.
There are in fact various types of closure which are distinguished by the type and number of surfaces of engagement between the barrel assembly and the break-action when the firearm is closed in the firing position.
Another type of closure has a plate inserted between the barrel assembly and the break-action. The plate is coupled to the barrel assembly and has the task of absorbing the energy of the barrel toward the break-action.
RU2235261, FR387630, DE2841938, DE4446906, DE19909580 and DE102007044993 disclose break-action guns with a closure block associated with the break-action.
However, those systems must still have, like all closure systems of the known type, a very precise construction and an accurate adjustment between the breech face of the barrels and the breech face of the break-action. Moreover, even in the plate closure system of the known type, the residual energy that the barrel generates forward after firing is withstood completely by the two hinge pivots mounted on the break-action, consequently stressing the structure of the break-action.